Research

My research focusses on the behavioural ecology of migratory fish. I work principally on European eel and brown trout / sea trout, employing acoustic telemetry and sonar technologies in field environments to improve our understanding of fish behaviour. I am particularly interested in the responses of diadromous fish to environmental stimuli (e.g. hydrodynamics, acoustics) and how these can be used to develop more effective fish guidance and passage technologies.

I conduct applied research and have a strong interest in translating findings into real world management applications. Broadly, my work is directed towards developing robust and practical solutions to mitigate for the impacts of anthropogenic structures (e.g. weirs, dams, water pumps and hydropower) on fish populations and facilitate the free movement of migratory fish. I work closely with partners at University College London, relevant public bodies (Environment Agency, Cefas), industry (water and power) and environmental NGOs (Wild Trout Trust, The Rivers Trusts, Atlantic Salmon Trust, Wildlife Trusts).

Research Interests:

fish behaviour

ecohydraulics

spatial ecology

fish guidance technologies

fish passage

animal tracking technologies

European Eel – current projects

Eel response to flow cues in disconnected waterbodies

Large disconnected waterbodies such as drinking water reservoirs hold significant stocks of European eel but there is often no feasible migration route by which adult eels can escape to undertake their seaward spawning migration. Given the importance of hydrodynamic cues in eel behaviour, the changeable and intermittent flow patterns present in reservoirs may influence eel distribution and provide attraction or deterrent to input and output sources.

Acoustic telemetry is being used to determine the distribution, movement patterns and residency characteristics of adult eels within a large reservoir. Eel data will be analysed in relation to concurrent environmental data such as input and output flows to quantify the relative influence of each on eel movement.

Greater understanding of eel distribution and response to flow cues in large lentic waterbodies will help inform the management of such populations, for example, by identifying screening priorities at pumps, enhancing trap and transport schemes, and informing adaptive management measures e.g. using flow cues to enhance the efficacy of out migration routes (bypasses).

Eels respond to the hydrodynamic gradients created at structures, for example rejecting areas of velocity acceleration and such responses may be exploited to guide eel away from deleterious areas (e.g. hydropower intakes and pumping stations) and towards safe passage routes.

Field experiments are being conducted to test the potential of flow manipulation to deflect eel on their approach to a pumping station. Acoustic positioning telemetry and sonar imaging technology are employed to monitor the fine scale behaviour of adult eel on the approach to the flow source. Eel swim paths generated from the positioning data will be analysed in relation to mapped flow fields to quantify how eels responded and determine if this approach has potential to work in other real world situations to guide eels towards safe passage routes.

Assessing the passability of structures to eel

An ongoing project is examining the movement patterns of European eel as they attempt to ascend and descend manmade river structures including flow gauging weirs and tide gates on the Rivers Stiffkey and Glaven in Norfolk. PIT telemetry is being used to track eel, enabling identification of route choice, passage efficiency, determine temporal variation, and explore the influence of physical and environmental parameters on barrier passage success.

Data will facilitate the prioritisation of barriers for future mitigation measures such as the installation of eel passes and modification of tide gates to enhance passage at key migration periods.

Sea trout– current projects

Understanding movements, barrier passage and habitat use of anadromous and non-anadromous trout in North Norfolk

The importance of salmonids originating from small streams for the wider European stock is poorly quantified, though growing evidence suggests that they make a significant contribution to the genetic diversity, and therefore resilience, of wider populations.

A telemetry study is underway to quantify the origin, distribution and migration characteristics of sea trout within North Norfolk rivers and associated coastal waters. Tracking of tagged individuals within freshwater and estuarine reaches will provide key information on fish movements, including: 1) temporal patterns of sea trout migration, 2) delay caused by structures, 3) migration rate, and 4) habitat use during freshwater and estuarine phases. Genetic and stable isotope analyses are being applied to determine the contribution of seatrout from small streams to the wider stocks.